Re: [POLL] Proposed syntax for timestamps with time zone info (was: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda)

[Ihor Radchenko <yantar92@posteo.net>]

Max Nikulin <manikulin@gmail.com> writes:

> On 01/02/2023 23:45, Ihor Radchenko wrote:
>> 
>> Note how `encode-time' TIME argument has both DST flag and the time zone
>> name:
>> 
>>     (SECOND MINUTE HOUR DAY MONTH YEAR IGNORED DST ZONE)
>> 
>> DST is necessary exactly in the ambiguous situations like I described,
>> when we must know if day saving time is in effect or not __in addition__
>> to time zone name.
>
> Warning: just be aware that sometimes DST is not enough to resolve 
> ambiguity. E.g. in the following example attempt to pass non-nil DST 
> signals an error:
>
> zdump -v Africa/Juba | grep 2021
> Africa/Juba  Sun Jan 31 20:59:59 2021 UT = Sun Jan 31 23:59:59 2021 EAT 
> isdst=0 gmtoff=10800
> Africa/Juba  Sun Jan 31 21:00:00 2021 UT = Sun Jan 31 23:00:00 2021 CAT 
> isdst=0 gmtoff=7200

Providing UTC offset will resolve the ambiguity in this scenario. So, we
are good. Unfortunately, there seems to be no way to detect such
ambiguities programmatically. Not using glibc, at least.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
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